even if direct_media_glare_mitigation=none is setted , asterisk still sends re-invite with sdp to incoming direction after getting 200 OK-ACK

direct_media_glare_mitigation
This setting attempts to avoid creating INVITE glare scenarios by disabling direct media
reINVITEs in one direction thereby allowing designated servers (according to this option) to
initiate direct media reINVITEs without contention and significantly reducing call setup time.
A more detailed description of how this option functions can be found on the Asterisk wiki https://wiki.asterisk.org/wiki/display/AST/SIP+Direct+Media+Reinvite+Glare+Avoidance
none
outgoing
incoming
direct_media_method
Method for setting up Direct Media between endpoints.
invite
reinvite - Alias for the invite value.
update

You are configuring the mitigation strategy, “none” disables that strategy. If you want to disable direct media then you use the “direct_media” option and Asterisk won’t send out a reinvite to either side to directly send the media.

IPv6 is not honestly something we test for with direct media and it’s likely noone has ever touched or confirmed before. If it’s not working then yes an issue should be open, but as always there is no time frame on when it would get looked into - in particular in this case because you’re likely the only one touching it.